The broad objective of this proposal is to determine how renal and splanchnic afferent axons, central preganglionic fibers, renal and splenic postganglionic neurons, and single and multineuronal integrative mechanisms interact within prevertebral sympathetic ganglia to synthesize the sympathetic neural commands which regulate renal function and splanchnic circulation. The areas of particular interest are: a) histochemical and electrophysiological localization within the solar plexus of the soma of renal and splenic postganglionic neurons, b) synaptic input to renal and splenic postganglionic neurons from splenic afferent fibers and from baroreceptors associated with the mesenteric circulation, c) characterization of integrative mechanisms within the solar plexus at both the single and multineuronal levels, and d) effects of angiotensin II and pharmacological compounds on synaptic transmission and integrative mechanisms within solar plexus ganglia. The general method of approach will be to histochemically locate within the solar plexus, the soma of postganglionic neurons having their axons in a particular nerve trunk and to use intracellular recording techniques to measure, in vitro, the somatic electrical activity of these and other prevertebral neurons.